Ioversol is disclosed as a useful nonionic X-ray contrast agent in U.S. Pat. No. 4,396,598, incorporated herein by reference. N,N'-bis(2,3-dihydroxypropyl)-5-[N(2-hydroxyethyl) glycolamido]-2,4,6-triiodoisophthalamide, more commonly called Ioversol has the following structure: ##STR1## In the production of Ioversol, purification columns are used to remove impurities from the crude Ioversol product following completion of the synthetic steps as described in U.S. Pat. No. 4,396,598. Approximately 11 per cent of the crude Ioversol produced is lost from the time it enters the purification plant to the final purification of the product. Besides this large loss of Ioversol during purification, the cost and time involved in the purification operations, such as regenerating and replacing the purification columns is significant. Large amounts of costly resins and large volumes of solutions are also necessary to regenerate the purification columns between uses. These costs are significant in the production of Ioversol.
An improved procedure which eliminates the need for costly purification columns to remove impurities from the crude Ioversol product following synthesis thereof is desired as an alternate and/or a more cost efficient method of producing Ioversol. It is, therefore, an object of the present invention to meet these needs.
Additional objects and features of the present invention will appear from the following description in which the preferred methods are set forth in detail in conjunction with the accompanying drawing.
FIG. 1 is a schematic cross-sectional view of a continuous deionization system.